summaryrefslogtreecommitdiffstats
path: root/drivers/clk/at91/clk-pll.c
blob: b4138fcacf495156a5a14d684cc2e66309b9be6f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
/*
 *  Copyright (C) 2013 Boris BREZILLON <b.brezillon@overkiz.com>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 */

#include <linux/clk-provider.h>
#include <linux/clkdev.h>
#include <linux/clk/at91_pmc.h>
#include <linux/of.h>
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>

#include "pmc.h"

#define PLL_STATUS_MASK(id)	(1 << (1 + (id)))
#define PLL_REG(id)		(AT91_CKGR_PLLAR + ((id) * 4))
#define PLL_DIV_MASK		0xff
#define PLL_DIV_MAX		PLL_DIV_MASK
#define PLL_DIV(reg)		((reg) & PLL_DIV_MASK)
#define PLL_MUL(reg, layout)	(((reg) >> (layout)->mul_shift) & \
				 (layout)->mul_mask)
#define PLL_MUL_MIN		2
#define PLL_MUL_MASK(layout)	((layout)->mul_mask)
#define PLL_MUL_MAX(layout)	(PLL_MUL_MASK(layout) + 1)
#define PLL_ICPR_SHIFT(id)	((id) * 16)
#define PLL_ICPR_MASK(id)	(0xffff << PLL_ICPR_SHIFT(id))
#define PLL_MAX_COUNT		0x3f
#define PLL_COUNT_SHIFT		8
#define PLL_OUT_SHIFT		14
#define PLL_MAX_ID		1

#define to_clk_pll(hw) container_of(hw, struct clk_pll, hw)

struct clk_pll {
	struct clk_hw hw;
	struct regmap *regmap;
	u8 id;
	u8 div;
	u8 range;
	u16 mul;
	const struct clk_pll_layout *layout;
	const struct clk_pll_characteristics *characteristics;
};

static inline bool clk_pll_ready(struct regmap *regmap, int id)
{
	unsigned int status;

	regmap_read(regmap, AT91_PMC_SR, &status);

	return status & PLL_STATUS_MASK(id) ? 1 : 0;
}

static int clk_pll_prepare(struct clk_hw *hw)
{
	struct clk_pll *pll = to_clk_pll(hw);
	struct regmap *regmap = pll->regmap;
	const struct clk_pll_layout *layout = pll->layout;
	const struct clk_pll_characteristics *characteristics =
							pll->characteristics;
	u8 id = pll->id;
	u32 mask = PLL_STATUS_MASK(id);
	int offset = PLL_REG(id);
	u8 out = 0;
	unsigned int pllr;
	unsigned int status;
	u8 div;
	u16 mul;

	regmap_read(regmap, offset, &pllr);
	div = PLL_DIV(pllr);
	mul = PLL_MUL(pllr, layout);

	regmap_read(regmap, AT91_PMC_SR, &status);
	if ((status & mask) &&
	    (div == pll->div && mul == pll->mul))
		return 0;

	if (characteristics->out)
		out = characteristics->out[pll->range];

	if (characteristics->icpll)
		regmap_update_bits(regmap, AT91_PMC_PLLICPR, PLL_ICPR_MASK(id),
			characteristics->icpll[pll->range] << PLL_ICPR_SHIFT(id));

	regmap_update_bits(regmap, offset, layout->pllr_mask,
			pll->div | (PLL_MAX_COUNT << PLL_COUNT_SHIFT) |
			(out << PLL_OUT_SHIFT) |
			((pll->mul & layout->mul_mask) << layout->mul_shift));

	while (!clk_pll_ready(regmap, pll->id))
		cpu_relax();

	return 0;
}

static int clk_pll_is_prepared(struct clk_hw *hw)
{
	struct clk_pll *pll = to_clk_pll(hw);

	return clk_pll_ready(pll->regmap, pll->id);
}

static void clk_pll_unprepare(struct clk_hw *hw)
{
	struct clk_pll *pll = to_clk_pll(hw);
	unsigned int mask = pll->layout->pllr_mask;

	regmap_update_bits(pll->regmap, PLL_REG(pll->id), mask, ~mask);
}

static unsigned long clk_pll_recalc_rate(struct clk_hw *hw,
					 unsigned long parent_rate)
{
	struct clk_pll *pll = to_clk_pll(hw);

	if (!pll->div || !pll->mul)
		return 0;

	return (parent_rate / pll->div) * (pll->mul + 1);
}

static long clk_pll_get_best_div_mul(struct clk_pll *pll, unsigned long rate,
				     unsigned long parent_rate,
				     u32 *div, u32 *mul,
				     u32 *index) {
	const struct clk_pll_layout *layout = pll->layout;
	const struct clk_pll_characteristics *characteristics =
							pll->characteristics;
	unsigned long bestremainder = ULONG_MAX;
	unsigned long maxdiv, mindiv, tmpdiv;
	long bestrate = -ERANGE;
	unsigned long bestdiv;
	unsigned long bestmul;
	int i = 0;

	/* Check if parent_rate is a valid input rate */
	if (parent_rate < characteristics->input.min)
		return -ERANGE;

	/*
	 * Calculate minimum divider based on the minimum multiplier, the
	 * parent_rate and the requested rate.
	 * Should always be 2 according to the input and output characteristics
	 * of the PLL blocks.
	 */
	mindiv = (parent_rate * PLL_MUL_MIN) / rate;
	if (!mindiv)
		mindiv = 1;

	if (parent_rate > characteristics->input.max) {
		tmpdiv = DIV_ROUND_UP(parent_rate, characteristics->input.max);
		if (tmpdiv > PLL_DIV_MAX)
			return -ERANGE;

		if (tmpdiv > mindiv)
			mindiv = tmpdiv;
	}

	/*
	 * Calculate the maximum divider which is limited by PLL register
	 * layout (limited by the MUL or DIV field size).
	 */
	maxdiv = DIV_ROUND_UP(parent_rate * PLL_MUL_MAX(layout), rate);
	if (maxdiv > PLL_DIV_MAX)
		maxdiv = PLL_DIV_MAX;

	/*
	 * Iterate over the acceptable divider values to find the best
	 * divider/multiplier pair (the one that generates the closest
	 * rate to the requested one).
	 */
	for (tmpdiv = mindiv; tmpdiv <= maxdiv; tmpdiv++) {
		unsigned long remainder;
		unsigned long tmprate;
		unsigned long tmpmul;

		/*
		 * Calculate the multiplier associated with the current
		 * divider that provide the closest rate to the requested one.
		 */
		tmpmul = DIV_ROUND_CLOSEST(rate, parent_rate / tmpdiv);
		tmprate = (parent_rate / tmpdiv) * tmpmul;
		if (tmprate > rate)
			remainder = tmprate - rate;
		else
			remainder = rate - tmprate;

		/*
		 * Compare the remainder with the best remainder found until
		 * now and elect a new best multiplier/divider pair if the
		 * current remainder is smaller than the best one.
		 */
		if (remainder < bestremainder) {
			bestremainder = remainder;
			bestdiv = tmpdiv;
			bestmul = tmpmul;
			bestrate = tmprate;
		}

		/*
		 * We've found a perfect match!
		 * Stop searching now and use this multiplier/divider pair.
		 */
		if (!remainder)
			break;
	}

	/* We haven't found any multiplier/divider pair => return -ERANGE */
	if (bestrate < 0)
		return bestrate;

	/* Check if bestrate is a valid output rate  */
	for (i = 0; i < characteristics->num_output; i++) {
		if (bestrate >= characteristics->output[i].min &&
		    bestrate <= characteristics->output[i].max)
			break;
	}

	if (i >= characteristics->num_output)
		return -ERANGE;

	if (div)
		*div = bestdiv;
	if (mul)
		*mul = bestmul - 1;
	if (index)
		*index = i;

	return bestrate;
}

static long clk_pll_round_rate(struct clk_hw *hw, unsigned long rate,
					unsigned long *parent_rate)
{
	struct clk_pll *pll = to_clk_pll(hw);

	return clk_pll_get_best_div_mul(pll, rate, *parent_rate,
					NULL, NULL, NULL);
}

static int clk_pll_set_rate(struct clk_hw *hw, unsigned long rate,
			    unsigned long parent_rate)
{
	struct clk_pll *pll = to_clk_pll(hw);
	long ret;
	u32 div;
	u32 mul;
	u32 index;

	ret = clk_pll_get_best_div_mul(pll, rate, parent_rate,
				       &div, &mul, &index);
	if (ret < 0)
		return ret;

	pll->range = index;
	pll->div = div;
	pll->mul = mul;

	return 0;
}

static const struct clk_ops pll_ops = {
	.prepare = clk_pll_prepare,
	.unprepare = clk_pll_unprepare,
	.is_prepared = clk_pll_is_prepared,
	.recalc_rate = clk_pll_recalc_rate,
	.round_rate = clk_pll_round_rate,
	.set_rate = clk_pll_set_rate,
};

struct clk_hw * __init
at91_clk_register_pll(struct regmap *regmap, const char *name,
		      const char *parent_name, u8 id,
		      const struct clk_pll_layout *layout,
		      const struct clk_pll_characteristics *characteristics)
{
	struct clk_pll *pll;
	struct clk_hw *hw;
	struct clk_init_data init;
	int offset = PLL_REG(id);
	unsigned int pllr;
	int ret;

	if (id > PLL_MAX_ID)
		return ERR_PTR(-EINVAL);

	pll = kzalloc(sizeof(*pll), GFP_KERNEL);
	if (!pll)
		return ERR_PTR(-ENOMEM);

	init.name = name;
	init.ops = &pll_ops;
	init.parent_names = &parent_name;
	init.num_parents = 1;
	init.flags = CLK_SET_RATE_GATE;

	pll->id = id;
	pll->hw.init = &init;
	pll->layout = layout;
	pll->characteristics = characteristics;
	pll->regmap = regmap;
	regmap_read(regmap, offset, &pllr);
	pll->div = PLL_DIV(pllr);
	pll->mul = PLL_MUL(pllr, layout);

	hw = &pll->hw;
	ret = clk_hw_register(NULL, &pll->hw);
	if (ret) {
		kfree(pll);
		hw = ERR_PTR(ret);
	}

	return hw;
}


const struct clk_pll_layout at91rm9200_pll_layout = {
	.pllr_mask = 0x7FFFFFF,
	.mul_shift = 16,
	.mul_mask = 0x7FF,
};

const struct clk_pll_layout at91sam9g45_pll_layout = {
	.pllr_mask = 0xFFFFFF,
	.mul_shift = 16,
	.mul_mask = 0xFF,
};

const struct clk_pll_layout at91sam9g20_pllb_layout = {
	.pllr_mask = 0x3FFFFF,
	.mul_shift = 16,
	.mul_mask = 0x3F,
};

const struct clk_pll_layout sama5d3_pll_layout = {
	.pllr_mask = 0x1FFFFFF,
	.mul_shift = 18,
	.mul_mask = 0x7F,
};